TIMBER TESTING 297 



Generally speaking, the following deductions 

 as regards density and strength may be 

 accepted : — 



1. Timbers in which the grain is closely 



twisted and interwoven are in general 

 very hard, dense and heavy ; high in 

 compressive strength both edgewise and 

 crosswise, and also in shearing strength 

 along the grain ; comparatively low in 

 moisture, and, relatively to the straight- 

 grained timbers, are lower in tensile 

 strength, and therefore to a certain extent 

 less strong where used as " beams." 



2. Timbers in which the fibres are straight 



and even, are relatively less hard and 

 dense, and are Hghter ; considerably 

 higher in moisture percentage when 

 green ; stronger in " tension," and there- 

 fore generally stronger as beams, but are 

 correspondingly lower in compressive 

 strength and in shearing strength along 

 the grain. 



3. Timbers lying mid-way between these two 



conditions, although not so dense and 

 hard as those coming under the first 

 heading, are in general stronger than 

 either. 



4. Timbers grown in dry districts have a low 



